The data in the accompanying table were sampled from U.S. News & World Report's 1996 story on the "Best Mutual Funds." The following variables are shown for each fund:
CAT (fund category):
1 = Aggressive growth; 2 = Long-term growth; 3 = Growth and income; 4 = Income.
LOAD (load status):
N = No load; L = Load.
VOL (volatility):
A letter grade from A+ to F indicating how much the month-to-month return varied from the fund's three-year total return: A+ = Least variability; F = Most variability.
OPI (Overall Performance Index):
An overall measure of the relative performance of each fund over the past 1, 3, 5, and 10 years. The higher the OPI, the better the performance.

a. Suppose that an ANOVA is to be performed to compare the average OPI values for the different fund categories. State precisely the ANOVA model. Is fund category a fixed- or random-effects factor?
b. Using the SAS output that follows, complete the ANOVA table.
c. Test whether the average overall performance indices (OPI) differ significantly across the four fund categories (CAT).
d. Use the Tukey-Kramer method to locate any significant differences between pairs of means. (Use a = .05.)